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Biomedical subjects

J Tamaoki

Publications and source records attributed to J Tamaoki.

At least 109 records · Page 6Linked to original sources
PubMed1995

Isoproterenol increases Cl diffusion potential difference of rabbit trachea through nitric oxide generation.

To determine whether nitric oxide (NO) formation is involved in Cl secretion across airway mucosa in response to beta adrenergic agonists, we studied the effect of isoproterenol (ISO) on the Cl diffusion potential difference of rabbit tracheal mucosa and measured NO formation by a highly specific electrode for this molecule in vivo. Perfusion of ISO on the tracheal mucosal surface increased the Cl diffusion potential difference, as determined in the presence of amiloride, in a dose-dependent fashion, the maximal increase from the base-line value being 12.1 +/- 1.7 mV (P < .001). Application of NG-nitro-L-arginine methylester (10(-3) M) decreased the Cl diffusion potential difference by itself and attenuated the subsequent response to ISO, causing a rightward displacement of ISO concentration-response curves, whereas NG-nitro-D-arginine methylester had no effect. This inhibitory effect of NG-nitro-L-arginine methyl-ester was reversed by L-arginine but not by D-arginine. Addition of ISO dose-dependently increased polarographic current and, hence, NO concentration in the perfusate, the maximal increase from the base-line levels being 178 +/- 10 nM. Histochemistry for NADPH diaphorase activity showed a strong staining within epithelial cells. These results suggest that NO formation may play a role in the beta adrenoceptor-mediated Cl secretion by tracheal mucosa.

Animals↗
PubMed1995

Effect of TJ-96, an anti-allergic herbal medicine, on tracheal transepithelial potential difference in vivo.

We studied the effect of Saiboku-to (TJ-96), an anti-allergic herbal medicine, on transepithelial potential difference of rabbit trachea and possible involvement of nitric oxide (NO) generation in vivo. Perfusion of TJ-96 on the tracheal mucosal surface increased PD in a concentration-dependent manner, the maximal increase from the baseline level and the concentration of TJ-96 required to produce a half-maximal effect (EC50) being 8.1 +/- 1.4 mV (mean +/- SE, P < 0.001) and 47 micrograms/ml. This effect was abolished by pretreatment with the Na channel blocker amiloride. NG-nitro-L-arginine methylester (L-NAME) but not NG-nitro-D-arginine methylester (D-NAME) inhibited TJ-96-induced increase in PD, and this inhibition was selectively reversed by L-arginine. These results suggest that TJ-96 stimulates Na absorption by airway epithelial cells probably through NO generation.

Amiloride↗
PubMed1995

Stimulation of opioid mu-receptors potentiates beta adrenoceptor-mediated relaxation of canine airway smooth muscle.

To elucidate the effect of an opioid on airway smooth muscle relaxant responses and its mechanism of action, we studied canine bronchial segments under isometric conditions in vitro. Addition of the opioid mu-receptor-specific agonist DAMGO (10(-5) M) or Tyr-D-Arg-phe-Lys-NH2 (10(-5) M) did not alter the resting tension or the contractile responses to Ach but augmented the relaxation induced by isoproterenol: the concentrations of isoproterenol required to produce a half-maximal effect were decreased from 1.9 +/- 0.6 x 10(-6) to 3.1 +/- 1.0 x 10(-7) M (P < .01) by DAMGO and from 2.1 +/- 0.4 x 10(-6) M to 4.3 +/- 0.7 x 10(-7) M (P < .01), by Tyr-D-Arg-phe-Lys-NH2. This effect of DAMGO was concentration-dependent and was abolished by naloxone or Cys2, Tyr3, Orn5, Pen7-amide, a mu-receptor antagonist. DAMGO likewise caused a leftward displacement of concentration-response curves for forskolin but was without effect on those for 3-isobutyl-3-methylxanthine and 8-bromo-cAMP. Also, DAMGO did not affect the relaxant responses to verapamil, nitroprusside or 8-bromo-cGMP. Incubation of bronchial smooth muscle with DAMGO (10(-5) M) potentiated the intracellular accumulation of cAMP induced by isoproterenol (10(-6) M) from 258 +/- 22 pmol/g tissue wt. to 420 +/- 27 pmol/g tissue wt. (P < .01), an effect that was abolished by naloxone. These results suggest that stimulation of opioid mu-receptors specifically augments beta adrenoceptor-mediated bronchodilation probably by acting at the site proximal to adenylate cyclase in the cAMP-dependent pathway.

Amino Acid Sequence↗
PubMed1995

[Airway epithelium and nitric oxide].

To measure the generation of nitric oxide (NO) by airway epithelial cells and to study the physiological role of NO in the regulation of epithelial functions, we studied ciliary motility of rabbit cultured tracheal epithelium in vitro and ion transport across tracheal mucosa in vivo. Isoproterenol dose-dependently increased ciliary beat frequency, as measured by photoelectric methods. Perfusion of tracheal mucosa with tachykinins increased the diffusion potential for chloride ions, as measured in the presence of amiloride under open-circuit conditions: the rank order of potency was neurokinin A > substance P >> neurokinin B. These responses to isoproterenol and to tachykinins were attenuated by pretreatment with NG-nitro-L-arginine methylester, and this attenuation was reversed by L-arginine. In contrast, NG-nitro-D-arginine methylester and D-arginine had no such effects. NO concentrations in the medium and perfusate were measured in realtime with an amperometric sensor specific to this molecule, and immersion of the electrode allowed detections of a polarographic current under unstimulated conditions. Addition of isoproterenol, neurokinin A, or substance P caused a rapid and dose-dependent increase in NO concentration. Histochemical examination for NADPH diaphorase activity in cultured epithelium showed strong staining within the cytoplasm. These results suggest that NO is spontaneously released from airway epithelial cells and that generation of this molecule may contribute to airway epithelial ciliary motility and chloride ion secretion mediated by beta-adrenoceptors and by tachyinin NK2 receptors.

Animals↗
PubMed1994

Effect of menthol on cytosolic Ca2+ levels in canine airway epithelium in culture.

Intracellular Ca2+ concentration ([Ca2+]i) in canine cultured tracheal epithelium in response to cyclic alcohols was measured by a fura-2 method. Menthol rapidly increased [Ca2+]i in a concentration-dependent fashion, the maximal increase from the baseline levels and the concentration of menthol required to produce a half-maximal effect (EC50) being 148 +/- 23 nM (mean +/- SE, p < 0.001) and 0.3 mM, respectively, whereas other cyclic alcohols including menthone and cyclohexanol had no effect. The menthol-induced increase in [Ca2+]i was not affected by verapamil but partially inhibited by low Ca2+ medium in the presence of EGTA. These results indicate that menthol specifically increases cytosolic Ca2+ in airway epithelium, which may be derived from intracellular Ca2+ stores.

Animals↗
PubMed1994

Role of K+ channel opening and Na(+)-K+ ATPase activity in airway relaxation induced by salbutamol.

To determine the role of K+ channel opening and Na(+)-K+ ATPase activity in the beta-adrenoceptor-mediated relaxation of airway smooth muscle, we studied canine bronchial segments under isometric conditions in vitro. Relaxant responses to salbutamol were not altered by glibenclamide or apamin but inhibited by charybdotoxin, where significant inhibition was observed only at salbutamol concentrations of less than 10(-6) M. In contrast, only the relaxations induced by salbutamol at 3 x 10(-6) M and greater were sensitive to ouabain. Relaxations produced by low and high concentrations of salbutamol were selectively attenuated by charybdotoxin and ouabain, respectively, in a concentration-dependent manner. These results suggest that both Ca(2+)-activated K+ channel and Na(+)-K+ ATPase may be operative in the airway relaxation induced by low and high concentrations of the beta-adrenergic agonist, respectively.

Albuterol↗
PubMed1994

Pertussis toxin-sensitive airway beta-adrenergic dysfunction by somatostatin.

To elucidate the effect of somatostatin and its mechanism of action on airway beta-adrenergic function, we studied canine bronchial smooth muscle under isometric conditions in vitro. Somatostatin (10(-6) M) inhibited the salbutamol-induced relaxation, so that the salbutamol concentration-response curves were displaced to higher concentrations (P < 0.01). This inhibition was dose dependent, the concentration of somatostatin required to produce a half-maximal effect being 10(-8) M. The relaxant responses to forskolin were likewise inhibited by somatostatin, but those to dibutyryl 3',5'--adenosine cyclic monophosphate (DB-cAMP), verapamil and nitroprusside were not. Somatostatin inhibited the salbutamol-induced accumulation of intracellular cAMP. These effects were abolished by the somatostatin antagonist cyclo [7-aminoheptanoyl-Phe-D-Trp-Lys-Thr (Bz)] or pertussis toxin. These observations suggest that somatostatin down-regulates beta-adrenergic function of airway smooth muscle through activation of an inhibitory guanine nucleotide (GTP)-binding regulatory protein, Gi, coupled to adenylate cyclase.

Adenylate Cyclase Toxin↗
PubMed1994

Stimulation by menthol of Cl secretion via a Ca(2+)-dependent mechanism in canine airway epithelium.

1. To investigate the effect of menthol on airway epithelial ion transport function, we studied the bioelectrical properties of canine cultured tracheal epithelium by Ussing's short-circuit technique in vitro. 2. Addition of menthol (10(-3) M) to the mucosal but not the submucosal solution increased the short-circuit current (Isc) from 6.2 +/- 0.9 to 14.0 +/- 2.2 microA cm-2 (P < 0.001), and this effect was accompanied by increases in transepithelial potential difference and conductance. The response was dose-dependent, with the maximal increase from the baseline value and the concentration required to produce a half-maximal effect (EC50) being 6.4 +/- 0.9 microA cm-2 (P < 0.001) and 40 microM, respectively. 3. Other cyclic alcohols, including menthone and cyclohexanol, had no effect on the electrical properties. 4. The menthol-induced increase in Isc was not altered by pretreatment of the cells with amiloride, indomethacin, or propranolol but was abolished by diphenylamine-2-carboxylate, furosemide or substitution of Cl with iodide in the medium. 5. Menthol (10(-3) M) increased cytosolic levels of free calcium ([Ca2+]i) from 98 +/- 12 to 340 +/- 49 nM (P < 0.01) in fura-2-loaded tracheal epithelium but did not affect the intracellular adenosine 3',5'-cyclic monophosphate content. 6. These results suggest that menthol stimulates Cl secretion across airway epithelium, probably through a Ca(2+)-dependent mechanism, and might thus influence mucociliary transport in the respiratory tract.

Animals↗
PubMed1994

Effect of long term treatment with oxitropium bromide on airway secretion in chronic bronchitis and diffuse panbronchiolitis.

BACKGROUND: Anticholinergic bronchodilator drugs improve lung function in chronic bronchitis but less is known of their effects on the volume and physical properties of sputum in conditions associated with excessive airway secretions. This study examines the effects of the regular use of oxitropium bromide in such patients. METHODS: The study was conducted in a parallel, double blind, placebo controlled fashion. Patients were divided into two groups: the first group (n = 17) received oxitropium bromide from a metered dose inhaler (two puffs three times daily; 100 micrograms/puff) for eight weeks, and the second group (n = 16) received placebo. Lung function was measured as forced expiratory volume in one second (FEV1) and vital capacity. In evaluating airway secretion, daily amount of expectorated sputum, percentage solid composition, viscoelastic properties including elastic modulus and dynamic viscosity, and sputum microbiology were determined. RESULTS: Oxitropium bromide increased FEV1 and decreased the mean (SE) sputum production from 61(4) to 42(3) g/day after treatment, whereas placebo had no effect. Bacterial density and sputum flora were unchanged, but solid composition and elastic modulus increased from 2.52(0.43)% to 3.12(0.34)%, and 68(12) dyne/cm2, respectively, in the group taking oxitropium bromide. CONCLUSIONS: Regular treatment with oxitropium bromide not only improves airflow limitation but also reduces sputum production, probably through the inhibition of both mucus secretion and water transport, the latter component being predominant.

Adult↗
PubMed1994

Angiotensin II 1 receptor-mediated contraction of pulmonary artery and its modulation by prolylcarboxypeptidase.

To determine the subtype of angiotensin II (ANG II) receptor involved in the contraction of pulmonary artery and to elucidate its possible modulation by endogenous peptidases, we studied canine isolated pulmonary arterial rings under isometric conditions in vitro. Addition of ANG II caused a concentration-dependent contraction, an effect that was not altered by the ANG II 2 receptor antagonist EXP655 but was depressed by the ANG II 1 receptor antagonist DuP 753 so that the ANG II response curves were displaced to higher concentration by 1.5-2.0 log U (P < 0.001). Pretreatment of tissues with the prolylcarboxypeptidase (PCP) inhibitor p-methylphenyl sulfonyl-fluoride potentiated the ANG II-induced contraction, with the concentration required to produce a half-maximal effect of ANG II being decreased from 4.1 +/- 0.9 x 10(-9) to 3.8 +/- 0.5 x 10(-10) M (P < 0.001), whereas other peptidase inhibitors such as p-chloromercuriphenyl sulfonic acid, amastatin, and phosphoramidon had no effect. The p-methylphenyl sulfonylfluoride-induced potentiation was abolished by the removal of endothelium, but it was still observed in the presence of NG-nitro-L-arginine methyl ester in the endothelium-intact tissues. The PCP activity in the tissues was reduced by the removal of endothelium from 645 +/- 88 to 91 +/- 29 nmol.mg protein-1.h-1 (P < 0.001), and cultured endothelium had the activity of 404 +/- 39 nmol.mg protein-1.h-1. These results suggest that ANG II contracts pulmonary artery via ANG II 1 receptor and that PCP localized to the endothelium may have a modulatory role in the ANG II-induced pulmonary vasoconstriction.

Angiotensin II↗
PubMed1994

Effects of prostacyclin and beraprost on ciliary motility of rabbit airway epithelium.

The effects of prostacyclin and its stable analog beraprost on ciliary beat frequency (CBF) of rabbit tracheal epithelium were studied by a microphoto-oscillation technique in vitro. Addition of these drugs increased CBF in a dose-dependent fashion: the maximal increase from the baseline value and the drug concentration required to produce a half-maximal effect were 13.3 +/- 2.0% (p < 0.05) and 1.8 +/- 0.4 x 10(-7) mol/l for prostacyclin and 30.8 +/- 3.4% (p < 0.001) and 1.6 +/- 0.5 x 10(-7) mol/l for beraprost. These effects were accompanied by the increase in intracellular cyclic AMP levels. Thus, prostacyclin and beraprost may stimulate ciliary motility and, hence, mucociliary transport through the production of cyclic AMP.

Animals↗
PubMed1994

Interleukin-1 beta inhibits airway smooth muscle contraction via epithelium-dependent mechanism.

To determine whether the cytokine interleukin (IL)-1 beta directly affects airway smooth muscle functions and, if so, what the mechanism of action is, we studied canine isolated bronchial segments under isometric conditions in vitro. Incubation of tissues with human recombinant IL-1 beta (10 ng/ml) for 150 min decreased the contractile responses to acetylcholine, histamine, and KCl. The inhibitory effect of IL-1 beta on the acetylcholine (10(-3) M)-induced contraction was concentration-dependent, the maximal decrease from the baseline contraction being 52 +/- 8% (mean +/- SD, p < 0.001) observed with 10 ng/ml IL-1 beta. Intracellular levels of cyclic AMP and cyclic GMP were not significantly altered by IL-1 beta. The IL-1 beta-induced inhibition of the contractile responses was not affected by pretreatment of tissues with indomethacin or propranolol, but it was greatly attenuated by mechanical removal of epithelium. These results suggest that IL-1 beta may play a protective role against bronchoconstrictor responses via epithelium-dependent mechanism such as the release of epithelium-derived relaxing factor.

Acetylcholine↗
PubMed1994

Effect of platelet-activating factor on intracellular free calcium in cow tracheal epithelium.

The effect of platelet activating factor (PAF) on the intracellular cytosolic levels of free calcium ([Ca2+]i) was studied in cultured epithelium from cow trachea. In fura-2-loaded cells, PAF (10(-9) to 10(-5) M), but not lyso-PAF, increased [Ca2+]i in a concentration-dependent manner, from 106 +/- 15 to 270 +/- 40 nM (P < 0.05). This [Ca2+]i response consisted of a transient increase that peaked within 15 s after addition and a subsequent sustained elevation that reached a plateau after 1 min. The potency for the sustained response was greater by approximately 1 log U than that for the transient response. Preincubation of the cells with the PAF receptor antagonist CV6209 (10(-6) M) inhibited the increase in [Ca2+]i. Ca(2+)-free medium (2 mM EGTA) totally abolished the sustained response to PAF, but it only partially inhibited the transient response. Verapamil (10(-5) M) also largely inhibited the sustained response. Moreover, PAF transiently increased inositol triphosphate (IP3) levels, peaking 10 s after addition. These data suggest that (1) a PAF-induced increase in [Ca2+]i is mediated via PAF receptors, (2) PAF causes both transient [Ca2+]i release from intracellular stores through IP3 production and sustained [Ca2+]i influx from extracellular solution, and (3) Ca2+ influx may be a major pathway of PAF-induced increase in [Ca2+]i in cow tracheal epithelium.

Animals↗
PubMed1994

[Effect of Sei-hai-to on ion transport in airway epithelial cells].

The effect of Sei-hai-to on ion transport in airway epithelial cells and its mechanism of action were investigated. Measurement of short-circuit current (Isc) using cultured epithelial cells from canine tracheal mucosa under short-circuit conditions showed that Isc was dose-dependently increased by the submucosal administration of Sei-hai-to. The response of Isc to this drug was not affected by pretreatment the cells with amiloride, but abolished by furosemide, or Cl-free condition. These results suggest that Sei-hai-to stimulates Cl ion transport selectively and may affect the subsequent movement of water across the airway mucosa to the lumen.

Animals↗
PubMed1994

[Cell-to-cell interaction in airway mucosa--effect of eosinophils on airway epithelial ion transport].

We examined the interaction between eosinophil-derived mediators and ion transport in airway epithelial cells. Eosinophils were obtained by peritoneal lavage from polymyxin B-treated guinea-pigs and were purified over discontinuous Percoll density gradients. The activated eosinophil supernatant was prepared with a two-stage method in the presence of A23187. The effects of eosinophil supernatant on the electric properties of cultured epithelial cells from cow trachea were examined in an Ussing chamber under short-circuit conditions. The eosinophil supernatant added to the serosal and mucosal sides increased the short-circuit current (Isc) in an eosinophil number-dependent manner (3 x 10(6), 10(7) eosinophils: delta Isc 9 +/- 1 microA/cm2, 18 +/- 3 microA/cm2). The response was inhibited by treatment of epithelial cells with diphenylamine-2-carboxylate but not by amiloride. The increase in Isc induced by the supermatant from eosinophils treated with indomethacin or the lipoxygenase inhibitor AA861 was significantly less than that induced by untreated eosinophils. These results indicate that activated eosinophils stimulate C1 secretion in airway epithelium via release of metabolites of arachidonic acid.

Animals↗
PubMed1994

[Continuous monitoring of nitric oxide release from airway mucosa].

There is increasing evidence that nitric oxide (NO) plays a role in the regulation of airway and vascular smooth muscle tone, pulmonary microvascular permeability, and host defense. However, it remains uncertain whether NO is actually released from airway mucosa. We therefore directly measured NO concentrations in the perfusate of rabbit tracheal mucosal surface, with an NO-selective electrode. The electrode was made of Pt/Ir alloy coated with a three-layered membrane that consisted of KCl, No-selective silicone resin, and a normal silicone membrane. Termination of tracheal perfusion with Krebs-Henseleit solution increased the electrical current derived from oxidation of NO at the electrode, and reperfusion rapidly decreased the current to the baseline value. Addition of L-NG-arginine methylester (L-NAME, 10(-3) M) to the perfusate decreased NO release, but D-NAME had no effect. Subsequent addition of L-arginine (10(-3) M) reversed the inhibition by L-NAME and greatly increased NO release above the baseline value. Histochemical staining to reveal NADPH diaphorase activity in the tracheal tissue showed a strong blue reaction mainly in the epithelial cells. These results suggest that NO is continuously released in the airway mucosal surface, probably from the epithelial cells rich in NO synthase.

Animals↗